Coil winding



. April 1945- H. E. JOHNSON COIL WINDING Filed Nov. 5, 1943 2 Sheets-Sheet 1 Inventor: HarolcLE. Johnson, by WNW is Attorney.

April 17, 1945. H. E. JOHNSON 1 2,374,018

COIL WINDING Fi led Nov; 5, 1943 2 Sheets-Sheet 2 Inventor Harold E. Johnson,

by W 6? .JMMZM H is Att Ofhey.

Patented Apr. 17, 1945 Harold E. Johnson, Lynn, Mass, asslgnor to General Electric Company, a corporation of New York Application November 5, 1943, Serial No. 509,143

3 Claims.

My invention relates to a coil winding for an electrical induction apparatus and to a method of making the winding.

Coil windings for electrical induction apparatus and particularly transformers of the instrument current type usually include a primary winding which has a small number of turns provided by a conductor of a relatively large cross section since the primary winding is connected in series with an electrical line. Since the primary winding carries a relatively large amount of current it must be rugged in construction. A pair of relatively rugged terminals are also usually connected to opposite ends of the primary winding for connection to the electrical line. .The instrument transformer usually also includes a core passing through a winding window of the primary winding with a secondary winding having a relatively large number of turns provided by a conductor of relatively small cross section since the secondary winding does not carry a very large amount of current.

It is therefore an obje t of my invention to provide an improved winding construction for an electrical induction apparatus which is particu larly adapted for a primary winding for an instrument transformer.

A further object of my invention is to provide an improved electrical induction apparatus having a primary winding which is simple in construction so as to facilitate its manufacture.

A further object of my invention is to Provide an improved method of forming a coil winding for an electrical induction apparatus.

Further objects and advantages of my invention will become apparent from the following description referring to the accompanying drawings, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

In the drawings Fig; 1 is a top view in partial section of an instrument transformer which is provided with an embodiment of my invention; Figs. 2 to 5, inclusive, illustrate the various steps of my method of producing the primary winding employed in the apparatus of Fig. 1; Fig. 6illustrates the primary winding employed in the transformer of Fig. i; Fig. '7 illustrates a modification of the coil of Fig. 6, and Fig. 8 illustrates the conductor employed to form the winding oi Fig. '7.

Referring more particularly to Fig. i of the drawings, I have illustrated an electrical induction apparatus which has particular application as an instrument transformer and includes a core having a pair of winding less In and II which are surrounded .by a pair of secondary or low voltage coils l2 and I3 and a pair of primary winding portions l4 andv I 5. The secondary winding portions l2 and I3 may be of any suitable construction snch as having a plurality of distributed turns around the winding legs I and H. The secondary windings are connected in series by the conductor l6 and suitable terminals are provided, which are not shown. for connecting the secondary windings to any suitable burden, which in the construction shown in Fig. 1. includes a suitable instrument such asan ammeter, wattmeter or a relay coil. A casing I! surrounds the core and coils and is provided with a pair of apertures through which extend the primary terminals l8 and I9.

As will be seen in the drawings the terminals l8 and I9 are symmetrically arranged orextend from opposite sides of the transformer construction and in order to provide a simple arrangement of obtaining an even number of electrical turns for the coil winding portions 14 and i I provide an improved primary winding construction which will now be described in relation to Figs. 2 through 5.

" As will be seen in Fig. 2, the coil winding portions H and I5 are provided by a pair of conductor straps 20 and 2|, the opposite ends of which are connected to the terminals l8 and I9. Thus the terminals [8 and 19 have depending or right angularly extending lug portions 22 and 23, respectively, as will be seen particularly in Fig. 6. To one face of the lug 22, an end 24 of the conducting strap 20 is attached in any suitable manner, such as by welding, and to the opposite face of the lug 22, an end 25 to the strap 2| is similarly attached. Also, to the lug 23 of the terminal 19 there is attached an end 25 of the strap 20 and to the opposite surface of the lug there is attached an end 21 of the strap 2|. It will also be noted that the terminals l8 and is are disposed with their terminal portions extending in opposite directions, and the straps 20 and 2| are so positioned that they form a pair of C-shaped members or U-shaped members with inwardly turned flanges during the step of the method as is shown in Fig. 2.

In order to form coil portions with the.conducting straps 20 and 2|, each of the terminals I8 and I 9 is rotated in the same direction, as is illustrated by the steps shown in Figs. 3, 4, and 5. Also so as to insure that the coil portions I4 and IE will have window portions 30 and 3!, respectively, through which extenmthe winding legs of the straps 20 and 2|.

the core legs.

l and .H, I provide winding mandrels 32 and 33 which have the same shape as the resulting window. These winding'mandrels it will be seen in Fig. Zare placed adjacent the lug surfaces 22 and 23. Thus when the terminals l8 and I9 are each rotated in the same direction, for ining provided by the end of the strap 23 andthe turn 35 being provided by the end of the strap 21. Whenthe terminals I 8 and I9 are rotated another QQ'degrees in the same'direction the ends of the conducting straps 20 and ii are then forced into relatively tight engagement around the lugs 22 and 23 as will be seen in Fi 4. Also the straps may be placed in tight engagement all along the central surface as is illustrated in Fig.

4 so as to facilitate the completion of the winding Thus when the terminals l8 and 13 are wound another 90 degrees, as is illustrated in Fig. 5, the central leg portion 40 of both straps 20 and 2| and the outer surface GI and 42 which surrounds the 'mandrels 32 and 33 respectively are brought into relatively tight engagement, asis shown in Fig. 5.

In order to facilitate the discernment between the straps 20 and 2|, arrows have been placed on the strap 2| so that it may be seen irom an inspection of Fig. how many turns are included in each of the coil portions l4 and I5. Thus with the construction illustrated in the drawings each of the conductors provides two electrical turns.

the terminals and then winding the conductors in the manner described the terminals are relatively tightly and snugly supported inside the coil windings and thus a very rugged construction is provided which will withstand relatively large short circuit forces.

It is to be understood that any suitable number i and 8 the terminals 43 and id have similar depending or lug portions 65 and d6, respectively, which are attached in any suitable man'- ner such as by soldering or welding to the ends of the strapdfl. The coil portions ll and% are then formed by winding the strap around a pair of.

I the various coil portions, as is shown in the this means a total of two electrical turns linking Also, from a. mechanical viewpoint'a half turn is provided for one of the coil portions and one and one-half turns for the other coil portions with each strap. It is to be understood, however, that by properly proportioning the sizes and number of straps in relation to the 1 size of the mandrel and the terminal lugs, any

suitable number of turns may be provided in the coil portions, and these even numbers of mefchanical turns are provided by odd numbers or {fractions of odd number. of turns for each of the straps 20 and 2!. Thus it will be seen, from a mechanical viewpoint, that if X is the number of turns provided for one of the coil portions by one of thestraps, X+l turns are provided by the same strap for the other coil portion. 1 This may be seen from an inspection of Fig. 3 where at this step, in the method one end-of each conductor After'the coils have been wound in the manner 7 illustrated in "Figs. 2 through 5, the mandrels '32 and 33 may be forced out of the coils thus providing a pair of coil portions with windows,

as is illustrated in the perspective view of Fig. 6.

I In order to form the complete electromagnetic induction apparatus as is illustrated in Fig. 1,

the core leg portions Ill and l I with the secondary windings l2 and I3 may be inserted in the windows 30 and 3i of the primary winding.

A further important advantage of the construction described above is that by attaching drawings, and in Fig. 7 it will be seen that this insulation is provided by employing sheets 41 and .48 of suitable insulating material, such as paper.

Any suitable number of turns may be provided with the coil construction, and in Fig.7 three electrical turns are provided which link the winding legs or approximately one and onehalf mechanical turns are provided for each of the coil portions 4! and 42. It will also be noted that in the construction as illustrated in Fig. 7, an odd number of electrical turns is provided while in the construction as illustrated in Figs. 1 through 6 an even number of electrical turns is provided. Also the construction in Fig. 7 has the similar important advantage that the terminals are each wound with the continuous conductor 50 that the terminals are inside'the convolutions so as to provide a very rugged construction which will stand relatively large short circuit forces.

Although I have shown and described particu-,

lar embodiments of my invention, I do not desire to be limited to the particular embodiments deof each of said strap conductors tosaid lug portions. said conductors being wound snugly forming a pair of coil portions of a coil winding. each of said straps providing one-half a mechanical turn for one coil and one. and one-half mechanical turns for the second 'coil so that each coil includes a total of two mechanical turns.

' 2. A winding for an electrical induction apparatus including a pair of snugly wound strap conductors providing a first and a second coil, one of said conductors providing X mechanical turns for one coil and X plus one turns for said second coil. said other conductor providing X mechanical turns for said second coil and X plus one turns for said first coil.

3.An electromagnetic apparatus including a core having a pair of winding legs, and a. pair of coil portions surrounding said legs, said pair or coll portions formed of a pair or snugly wound conductors, one of' said conductor-s providing X mechanical turns for one coil and X plus one turn; for said second coil, said other conductor providing X mechanical turns for said second coil 5 portion and X plus one turns for said first coil portion.

HAROLD E. JOHNSON. 

